Since secondary batteries such as lithium-ion secondary battery become familiar and increase battery capacity, higher reliability is required for safety. JP 2009-199960 A discloses a lithium-ion secondary battery in which an insulating film having no ion permeability is placed at a position where a non-application part faces an application part of negative electrode active material. Such a lithium-ion secondary battery makes it possible to suppress intercalation of the electrolytic ion liquid to the negative electrode active material even after cycles of charge and discharge and to prevent the swelling and delamination. JP '960 discloses an example of an adhesive tape made of polyimide as an insulating film. As another example of such an adhesive tape, JP 2005-126452 A discloses an adhesive tape made by applying acrylic series or silicone series pressure-sensitive adhesive (hereinafter, referred to as PSA) to a film such as biaxially-oriented polypropylene film.
However, when such conventional insulating tapes are used to adhere, PSA of the insulating tape might stick to blades of a cutter in cutting the electrode with the insulating tape so that the PSA itself or neighbor foreign materials caught by the PSA might be mixed into the battery so as to affect the battery performance.
In view of the above-described problem, there is a need to provide a secondary battery, a method of manufacturing a secondary battery and insulating films where foreign materials are prevented from being mixed into the battery.